Spacer distributing apparatus for fabricating liquid crystal display device

ABSTRACT

A method of fabricating a liquid crystal display device includes forming a thin film transistor on a first substrate, forming a color filter on a second substrate, and forming a spacer on one of the first and second substrates, the spacer being formed by a distributing apparatus, and forming a liquid crystal layer between first and second substrates.

This application is a Continuation of co-pending application Ser. No.10/299,849, filed on Nov. 20, 2002, the entire contents of which arehereby incorporated by reference and for which priority is claimed under35 U.S.C. § 120.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a spacer distributing apparatus used infabricating a liquid crystal display device (hereinafter, as LCD) andparticularly, to a distributing apparatus capable of preventing a spacerfrom being contaminated and adversely affecting the distribution of thespacer.

2. Description of the Related Art

Currently, the range of application of the liquid crystal display deviceis enlarged due to the rapid development of the liquid crystal displaydevice and the liquid crystal display device is installed in mostportable electronic devices due to its light weight. Accordingly,developing the manufacturing technology with a reduced cost and improvedproductivity is an essential criteria.

Generally, as shown in FIG. 1, a liquid crystal display apparatusincludes an upper substrate 30 in which a color filter is formed, alower substrate 10 in which a thin film transistor array is formed and aliquid crystal layer 22 which is disposed between the two substrates 10and 30.

On the outer surface of the two substrates 10 and 30, polarizers 11 and31, for linearly polarizing visible rays, are respectively attached.That is, the polarizer 31 is attached to a surface of the uppersubstrate 30 and a color filter 32 and a common electrode 33 are formedon the opposite surface where the polarizer is not attached. Also, apolarizer 11 is attached to a surface of the lower substrate 10. On theopposite surface where the polarizer is not attached, a TFT array,including a plurality of gate bus lines 12, a plurality of data buslines 13, a switching device A, a pixel electrode 16 and the like isformed.

The TFT includes three electrodes including a gate, source and drain, anamorphous-Si for forming a conductive channel which has a current flowbetween the source electrode and drain electrode caused by an electricfield when a positive voltage is applied to the gate electrode, and apassivation layer for protecting the device.

The LCD device with the above composition is formed by attaching thelower substrate which is composed of the TFT and the pixel electrode,and the upper substrate which is a color substrate having a liquidcrystal disposed therebetween. An orientation film is formed on opposingsurfaces through which the upper and lower substrates face each other,and a sealant is formed on the upper substrate. On the lower substrate,the spacer is formed and then the two substrates are attached.

FIG. 2 is a cross-sectional view showing an LCD device which is formedby attaching an upper substrate and a lower substrate.

On the opposing surfaces of the upper substrate 30 in which the colorfilter is formed, and a lower substrate 10 in which the TFT array isformed, an alignment layer 36 is printed. Also, the sealant 38 which isprinted in a non-active region forms a gap between the two substrates,and prevents leakage of liquid crystal (not shown) which is injectedbetween the two substrates. Also, circular spacer 40 is uniformlydistributed between the two substrates so that the two substratesmaintain a predetermined interval.

Also, to maintain a proper thickness of the liquid crystal layer in anLCD device, the spacer is distributed to control the gap between the twosubstrates, and prevent display spots and degradation of visuality,caused by a nonuniformity of the thickness of the liquid crystal layer.

Recently, the LCD device requires a high performance, such as a highcontrast ratio, an expansion of the viewing angle field, and a highresolution that enables a uniform display without a display defectionover the whole device. To insure high performance of the LCD device, itis necessary to control the interval between the substrates as apredetermined value, and to insure high resolution, it is necessary tocontrol the interval between the substrates to be uniform in the wholedevice. Therefore, to improve display performance, it is very importantthat a spacer is uniformly distributed in the whole area of thesubstrate.

In the LCD device, as the spacer, 10 to 2000 particles having a uniformdiameter of from several microns to several tens of microns areuniformly distributed or spread in 1 mm² as a single step to form aninterval, so that the liquid crystal can be injected between the glasssubstrates or between plastic (organic glass) substrates, or between theplastic substrate and the glass substrate. As the spacer for the liquidcrystal, various plastic particles or silica particles can be used.

Generally, as the method for distributing the spacer, there are the wetdistribution method and the dry distribution method. The wetdistribution method suspends the spacer for the liquid crystal in asolution such as Fron under a colloidal condition and uniformlydistributes the resultant product on the substrate in a liquid state.Then, a predetermined amount of spacer is uniformly distributed on thesubstrate as a single step by vaporizing the solution. However, sincethe usage of Fron is limited due to environmental problems, thefollowing dry distribution method is commonly used.

The dry distribution method is performed by distributing the spacerwithout, so-called lumps by charging it positively or negatively. As anexample, when a high voltage is generated in an electrode at the end ofthe nozzle and the air at the circumference thereof is ionized, thespacer carried by the air collides with the negative ions in the air andis negatively ionized. The negatively ionized spacers are led to asubstrate on the supporter which is grounded so that they repel eachother. The spacers which are negatively ionized on the substrate arepositioned at regular intervals by the repulsive force among each other.

FIG. 3 is a view showing an example of a general spacer distributingapparatus.

As shown in the drawing, in the spacer distributing apparatus for aliquid crystal, a stage or table 41 which is grounded, is positionedwithin the lower portion of a hermetically sealed chamber 40 and asubstrate 51 which is a distributed material which is applied to thetable is grounded so that the spacer which is a charged fine powder isprecisely attached to the grounded substrate 51.

A nozzle unit 42 which freely moves in the left and right directions andfront and rear directions on a flat panel is installed at the upperportion of the chamber 40. The nozzle unit 42 is connected to a spacersupply unit 43 by a SUS pipe 44 to discharge the spacer for the liquidcrystal. The spacer is carried with an air stream of gas, such as air ornitrogen, from the spacer supply unit 43 to distribute the spacer on thesubstrate 51.

FIG. 4 is an enlarged view showing the nozzle unit 42. The nozzle unit42 which is installed at the upper center portion of the chamber 40,includes a nozzle 46 which is composed of a hollow pipe, a supporter 45for supporting the nozzle 46, a ball bearing 47 which is insertedbetween the nozzle 46 and supporter 45 so that the nozzle 46 can befreely moved in the left and right directions and front and reardirections, a driving unit (for instance, a motor) for driving thenozzle 46 in the multiplicity of directions, and a cover 49 which coversthe nozzle 46.

The cover 49 is attached to prevent the introduction of foreignmaterials or dust into the inside of the chamber 40 between the nozzle46 and the supporter 45 when the spacer is distributed to the substrate51 as the nozzle 46 is moved in the left and right directions and thefront and rear directions. The cover 49 is called a dust cover.

However, when the cover 49 is used for a long time, tearing of the cover49 occurs in the connection between the nozzle 46 and cover 49 due tothe frequent movement of the nozzle 46. Therefore, foreign materials canpenetrate through the tearing crevice whereby the inside of the chamber40 becomes polluted.

When the cover 49 becomes torn due to the continuous rotation of thenozzle 46, the spacer which was distributed and lumped in the torn part(A) falls onto the substrate, causing a serious defect in the surface ofthe LCD.

SUMMARY OF THE INVENTION

Therefore, an object of the present invention is to provide a spacerdistributing apparatus, capable of preventing tearing of a cover to beuniformly positioned on a substrate without producing lumps of thespacer material, by constructing the structure of a dust cover toprevent the introduction of foreign materials into the nozzle unit. Thedust cover has stepped configuration.

To achieve these and other advantages and in accordance with the purposeof the present invention, as embodied and broadly described herein,there is provided a spacer distributing apparatus for fabricating aliquid crystal display device, including a chamber, a table positionedinside the chamber, a spacer supply unit installed outside the chamber,a nozzle having a dust cover, the dust cover being installed at theupper portion of the chamber, and a SUS pipe connecting the nozzle unitwith the spacer supply unit. The nozzle unit includes a nozzle supporterfor supporting the nozzle and the dust cover, which has steppedconfiguration, is utilized to protect the nozzle unit.

The table is positioned in the lower portion inside the chamber. Also,the table is grounded so that the substrate disposed on the table isalso grounded to precisely attach the spacer for the liquid crystal,which is a charged fine powder.

The spacer supply unit is installed outside the chamber and supplies thespacer to the nozzle unit.

In the method of supplying the spacer, a gas such as air or nitrogen issupplied from the outside to the spacer supply unit and the pressureinside the spacer supply unit is increased. Therefore, the spacer forthe liquid crystal is carried with the air stream of the gas and issupplied to the nozzle unit through the SUS pipe. The spacer, which issupplied to the nozzle unit, is distributed on the substrate through thenozzle of the nozzle unit.

In the nozzle unit which is composed of the nozzle supporter, nozzle,bearing, and stepped cover, the supporter supports the nozzle and thebearing which is installed between the nozzle and the nozzle supporterenabling the nozzle to freely move in the X and Y directions. Themovement of the nozzle is performed by the driving unit which isinstalled on the nozzle supporter.

The cover which is attached to the center of rotation of the nozzleprevents the introduction of foreign materials into the chamber and hasstepped structure for flexibly coping with the rotation of the nozzle.

It is desirable that the spacer distributing apparatus, in accordancewith the present invention, is applied to the dry distribution methodbut it can also be applied to the wet distribution method.

The foregoing and other objects, features, aspects and advantages of thepresent invention will become more apparent from the following detaileddescription of the present invention when taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from thedetailed description given hereinbelow and the accompanying drawingswhich are given by way of illustration only, and thus are not limitativeof the present invention, and wherein:

FIG. 1 is a schematic view showing a general liquid crystal display(hereinafter, as LCD) device;

FIG. 2 is a cross-sectional view showing an LCD device which is formedutilizing an upper substrate and a lower substrate;

FIG. 3 is a schematic view showing a general spacer distributingapparatus;

FIG. 4 is an enlarged view showing the nozzle unit of FIG. 3;

FIG. 5 is a schematic view showing a spacer distributing apparatus forfabricating a liquid crystal display device in accordance with thepresent invention;

FIG. 6A is an enlarged view showing the nozzle unit of FIG. 5 accordingto first embodiment;

FIG. 6B is an enlarged view showing the nozzle unit of FIG. 5 accordingto second embodiment; and

FIG. 7 is a view showing a scanning locus of the nozzle unit.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference will now be made in detail to the preferred embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings.

FIG. 5 is a view showing a spacer distributing apparatus for fabricatinga liquid crystal display device in accordance with the presentinvention.

As shown in the drawing, the spacer distributing apparatus forfabricating the liquid crystal display device in accordance with thepresent invention includes a chamber 40, a table 41 which is positionedinside the chamber 40, a spacer supply unit 43 for supplying the spacerto the chamber 40, a nozzle unit 42 which is installed in the upperportion of the chamber 40 for spraying the spacer which is supplied fromthe spacer supply unit 43 to the stage 41, and a SUS pipe 44 forconnecting the spacer of the spacer supply unit 43 with the nozzle unit42.

The nozzle unit 42 includes a nozzle 46, a nozzle supporter 45 forsupporting the nozzle 46, and a dust cover 49 which covers theconnection of the nozzle 46 and the nozzle supporter 45. The dust coverhas a dual stepped structure which accommodates the shape of the nozzle46 and the nozzle supporter 45.

The dust cover 49 prevents the inflow of dusts or foreign materialsthrough the contact surface of the nozzle 46 and the nozzle supporter45. Also, according to the frequent movement of the nozzle, the dustcover 49 is formed in a dual stepped structure along the shape of thenozzle 46 and the nozzle supporter 45 to prevent damage such as thetearing of the dust cover 49.

The table or stage 41 is grounded and positioned inside the lowerportion of the chamber 40 and precisely attaches the spacer which isdistributed through the nozzle 46 on a grounded substrate 51 bygrounding the substrate 51 on the stage.

In the upper portion of the chamber 40, the nozzle unit 42 and thespacer supply unit 43, which can freely fluctuate in the left and rightdirections and the front and rear directions on a flat substrate, areconnected to the SUS pipe 44, thus distributing the spacer on thesubstrate 51 by discharging the spacer, which is carried with a streamof gas such as air or nitrogen from the spacer supply unit 43, throughthe nozzle 46 of the nozzle unit 42.

The spacer supply unit 43 is provided outside and separate from thechamber 40 and supplies the spacer to the nozzle unit 42. By followingthe method for supplying the spacer, when the pressure inside the spacersupply unit 43 is increased due to the inflow of a gas, such as air ornitrogen, from the outside to the spacer supply unit 43, the spacersupply unit 43 supplies the spacer for the liquid crystal, which iscarried with the air stream of gas, through the SUS pipe 44 connectingthe spacer supply unit 43 and the nozzle unit 42, to the nozzle unit 42and the nozzle 46 to be distributed on the substrate 51.

Hereinafter, the nozzle unit 42 including the nozzle 46, the nozzlesupporter 45 and the dust cover 49 will be described with reference toFIGS. 6 a and 6 b showing in detail an enlarged view of the nozzle unit42.

As shown in the FIG. 6 a, the nozzle unit 42 includes the nozzlesupporter 45, the nozzle 46 and the cover 49. A driving unit 48 forfreely moving the nozzle 46 in the front and rear directions and in theleft and right directions is positioned beside the nozzle unit 42.

The nozzle supporter 45 supports and fixes the nozzle 46 to the chamberand a bearing 47 is installed between the nozzle 46 and the nozzlesupporter 45 so that the nozzle 46 can be freely moved in the front andrear directions and the left and right directions. The movement of thenozzle 46 is controlled by the driving unit 48 which is installed on thechamber 40.

The dust cover 49 which is attached to the nozzle 46 reduces the adverseeffects caused by the collection of foreign material thereby minimizingthe deformation of the shape caused by the movement of the nozzle 46.The dust cover is formed in a dual stepped structure 50 which flexiblycopes with the rotation of the nozzle 46.

Generally, the nozzle 46 is moved in the left and right directions andin the front and rear directions to distribute spacer on the substrate.At this time, the foreign material collecting portion of the cover 49,as shown in FIG. 4, is torn by frequent movement of the nozzle 46. Toprevent this, the cover 49 is formed as a dual stepped structure 50.

The cover 49 formed as above, prevents the inflow of foreign materialinto the chamber 40. Since it is made of rubber or a urethane material,free movement of the nozzle 46 can be flexibly accommodated and since itis formed as a dual stepped structure 50, the shape of the cover 49 ishardly changed, in spite of the fluctuations of the nozzle 46.

Therefore, since the cover 49 is not torn, even if the nozzle 46 is usedfor a long period of time, the conventional problems whereby foreignmaterials penetrate through the torn cover, are avoided. Also, a spacerwhich otherwise may collect around the torn cover and eventually fall onthe substrate, can also be eliminated.

FIG. 6 b shows a nozzle portion having a dust cover 49 a which is formedin a triple stepped structure 50 a. An identical reference numeral isgiven to the identical part as in the first embodiment (FIG. 6A), anddifferent points will be described. As described above, in case the dustcover 49 a is formed in the triple stepped structure 50 a, it could notsmoothly cope with frequent movement of the nozzle, compared with thedual stepped structure 50.

In the present invention, the structure of the dust cover is not limitedas the dual or triple stepped structure. That is, the shape of the dustcover can be changed according to the shapes of the nozzle, supporterand the like, which are covered by the dust cover.

The distribution process of the spacer by the spacer distributingapparatus can be described as follows.

Firstly, the spacer which, is stored in the spacer supply unit 43,passes through the SUS pipe 44 to the nozzle 46 and is sprayed throughthe nozzle 46. At this time, the pressure of the gas, e.g., air ornitrogen, in the spacer supply unit 43 is increased and accordingly, thespacer which is carried with the stream of gas is supplied to the nozzle46. When the spacer is supplied to the nozzle 46, the nozzle 46 evenlydistributes the spacer onto the substrate 51 by moving in the front andrear/left and right directions, namely, X and Y directions, using thedriving unit 48 which is installed in the upper potion of the chamber40.

In the method of distributing the spacer on the substrate 51, either thestage on which the substrate is positioned is fixed and the nozzle 46 ismoved, or the stage 41 on which the substrate 51 is positioned is movedand the nozzle 46 is fixed. Also, the nozzle 46 and the stage 41 can besimultaneously moved.

FIG. 7 is a pattern diagram showing a zigzag shape or serpentineconfiguration of the scanning locus of the spacer distributed on thesubstrate due to the movement of the nozzle 46 or the stage 41 in theleft and right/front and rear directions. It can be seen that thescanning locus is the locus of the extension line of the center axisline of the nozzle 46 for distributing the spacer, and its intersectionpoint on the substrate surface. The scanning locus is enabled bycontrolling the distributing of the spacer on the substrate 46 using thedriving unit 48.

As the nozzle 46 moves in the X and Y directions, and the movements ofthe nozzle in the X and Y directions are synthesized, the spacer isdistributed on the substrate 51 in the path shown in FIG. 7.

At this time, to prevent the introduction of foreign material into thechamber 40 and in the bearing 47 which is positioned at the rotationcenter of the nozzle 46, a cover 49, which is formed in steppedconstruction, is attached, in part, to the nozzle 46, and accordingly,there is no deformation of the shape of the cover 49 in spite of thefree movement of the nozzle 46.

As described above, in accordance with the present invention, byreducing the radius of the foreign material collecting area and byforming a cover which is attached to the nozzle center portion of thenozzle, the spacer distributing apparatus for liquid crystal, whichrequires the free movement of the nozzle, can be effectivelyaccommodated and the problem whereby the cover is torn by the movementof the nozzle, permitting the introduction of foreign material into thechamber, can be avoided.

Also, the defection in the distribution of the spacer on the substratecan be prevented by preventing the spacer from becoming lumped aroundthe torn cover and falling onto the substrate as the nozzle moves.

As the present invention may be embodied in several forms withoutdeparting from the spirit or essential characteristics thereof, itshould also be understood that the above-described embodiments are notlimited by any of the details of the foregoing description, unlessotherwise specified, but rather should be construed broadly within itsspirit and scope as defined in the appended claims, and therefore allchanges and modifications that fall within the metes and bounds of theclaims, or equivalence of such metes and bounds are therefore intendedto be embraced by the appended claims.

1. A method of fabricating a liquid crystal display device, comprising:forming a thin film transistor on a first substrate; forming a colorfilter layer on a second substrate; forming a spacer on one of the firstand second substrates, the spacer being formed by a distributingapparatus; and forming a liquid crystal layer between the first andsecond substrates, wherein the distributing apparatus includes achamber, a table, a nozzle unit having a nozzle, a dust cover formed tosubstantially correspond to the shape of the nozzle and a spacer supplyunit.
 2. The method of claim 1, wherein the table is positioned in thechamber accommodating one of the first and second substrates.
 3. Themethod of claim 1, wherein the nozzle unit is operatively associatedwith the chamber above the table.
 4. The method of claim 1, wherein thenozzle extends into the chamber.
 5. The method of claim 1, wherein thespacer supply unit is operatively connected to the nozzle unit.
 6. Themethod of claim 1, wherein the nozzle is supported by a nozzlesupporter, and the dust cover substantially follows the shape of thenozzle and the nozzle supporter.
 7. The method of claim 6, furthercomprising providing a bearing between the nozzle and the nozzlesupporter.
 8. The method of claim 6, wherein the dust cover has astepped structure.
 9. The method of claim 7, wherein the dust cover hasa multi-stepped structure.
 10. The method of claim 8, wherein the dustcover has a dual-stepped structure.
 11. The method of claim 8, whereinthe dust cover has a triple-stepped structure.
 12. The method of claim1, wherein a driving unit is operatively connected to the nozzle. 13.The method of claim 1, wherein the dust cover is formed of one of arubber material and a urethane material.
 14. The method of claim 1,wherein the nozzle is free to move in all directions.
 15. The method ofclaim 1, wherein the nozzle is free to move in front and rear/left andright directions.
 16. The method of claim 1, wherein an SUS pipe isconnected to the spacer supply unit and the nozzle unit.
 17. The methodof claim 1, wherein the table is positioned in the lower portion of thechamber and is free to move in left and right directions and front andrear directions.
 18. The method of claim 1, wherein the table ispositioned in the lower portion of the chamber and is free to move inall directions.
 19. The method of claim 1, wherein the table is groundedto ground the one of the first and second substrates.
 20. The method ofclaim 1, wherein the spacer that is stored in the spacer supply unit issupplied to the nozzle unit by providing a means for increasing thepressure inside the spacer supply unit.
 21. The method of claim 20,wherein the means is provided for supplying gas to the spacer supplyunit.